Surface Dilation and Fluid-Dynamical Behavior of Newtonian Liquids in an Overflowing Cylinder: II. Surfactant Solutions

• Published in: Journal of colloid and interface science 1994, Vol.165 (1), p.221-228
• Main Authors: Bergink-Martens, D.J.M., Bos, H.J., Prins, A.
• Format: Article
• Language: English
• Subjects: Geïntegreerde levensmiddelentechnologie en -fysica; Integrated Food Science and Food Physics
• ISSN: 0021-9797; 1095-7103
• DOI: 10.1006/jcis.1994.1222

The overflowing cylinder technique provides a characteristic image of the surface dilational behavior of the solution under investigation. The image is considered to be relevant to many practical processes. Dealing with pure liquids in the overflowing cylinder the surface expansion is fully determined by the bulk flow (see Bergink-Martens et al., J. Colloid Interface Sci. 138, 1 (1990)). In the presence of surface active components, however, the surface itself contributes to the surface flow. The propulsion mechanism changes completely, because a surface tension gradient is generated which induces a considerable acceleration of the free surface according to the Marangoni effect. In this paper the relation between the surface tension gradient and the resulting surface expansion rate is theoretically analyzed and experimental results are discussed in the perspective of the theoretical treatment. The surface expansion rate is measured by means of an adapted differential laser Doppler method which is successfully applied to the overflowing cylinder technique.